Demon Heart
by Kuro-Cha'Nay'Nay
Summary: Sebastian has everything he could possibly want- A loving mate, a beautiful child, and a good home. But what happens when all of it is taken away in an instant? In truth, a demon's heart can only take so much. /Oneshot, yaoi, mpreg in the first scene/.


**Warnings:** OOC-ness, Violence, Character death.

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"Just a little more, Ciel. One more push. You can do it." Sebastian soothed, gently massaging the boy's hips.

"Ungh!' The younger demon stifled a scream as he gave one last ferocious heave before collapsing back against the bed in exhaustion. A loud, familiar wail pierced the air as Sebastian worked quickly to remove the baby from Ciel.

"Good work, Ciel, it's out. Please give me one moment…"

Ciel groggily lifted his head to see his mate hovering over him, a smile on his face and their squirming newborn in his arms. "Ciel, meet your new daughter."

"I-It's a girl?" Ciel shakily took the child into his arms, quickly observing her features. Her head bore small, black locks of hair, and her eyes glowed a familiar dark blue. Her facial shape greatly resembled Ciel's, as well.

"Isn't she beautiful? She looks just like you. Well, minus the hair color." Sebastian teased, leaning down to place a kiss on his forehead. "Indeed, she does." Ciel murmured, relieved that the little girl was finally starting to calm down. Cuddling his new daughter, he let out a comfortable sigh and leaned back against the pillows, eyes slowly drifting shut. Sebastian smiled and gently stroked his cheek before turning away. "Rest a bit, love. I'll go make up a bottle for her and warm up some tea for you. Later, if you feel up to it, we can discuss na-"

"Layva." Sebastian paused and turned back to Ciel. "Pardon?"

"I've already decided. I want her name to be Layva." Ciel replied, opening his eyes as he yawned. He smirked when he saw the confused look on Sebastian's face. "What, you don't think it's pretty? I find it to be rather nice." Sebastian shook his head. "No, I do like it. It just seems so… _Random_. Where did you get it from?"

"I just made it up." Ciel grinned. "A child that was made by two ravishing demons such as ourselves ought to have an interesting name, right?" Sebastian chuckled, watching the boy's eyes close once more. "Yes, I suppose." He walked back over to gently tuck his mate in. "Look. You're a little bit delirious, and I don't want you overexerting yourself. We can talk about other names, later, if you-"

"No. The name stays." Ciel insisted, muttering a few more words before drifting off into a deep sleep. "All I want.. Is you… And Layva…" Sighing, Sebastian gently lifted the child from his arms and pulled the two of them into a comforting hug.

_I'm so happy to have the both of you in my life… I never thought I would have this much love to share with anyone besides myself._ He leaned down and planted a small kiss on his lips.

_I love you, Ciel Phantomhive… I hope I can stay forever at your side, not as your butler, but as your eternal companion. _

Sebastian took a breath of the sweet, clean air. It was a decent morning, and he had just come back from hunting a few delectable souls. Fortunately, his stomach was filled to the brim.

It had been sixth months since Layva was born, and she was already making so much progress with her demonic abilities. The man smiled at the memory of his daughter swallowing her first soul at barely three months old.

"She sure is growing up fast," Sebastian murmured, pushing a strand of hair away from his face. Smirking, he imagined what it would be like if they had another little demon running around. He and Ciel had discussed having another child, but they had decided to wait until Layva was at least a year old.

_I guess we'll just have to wait and see. _Sebastian stood up and turned in the direction of his home. _Well, I suppose I'd better get back… Ciel is probably wondering where I am._

Suddenly, Sebastian froze and fell to his knees in shock. Trembling, he lifted his hands and tightly gripped his upper arms. Another demon was near. He could sense him. The scent he caught was strangely familiar, and it belonged to a monster that he knew all too well…

"Claude." Sebastian choked out, eyes widening in total confusion as the demon stepped out from behind a tree, a wicked grin on his face. "How-! W- What are you doing here? I _k-killed _you."

"There are always ways out of things, Mister Michaelis, things that someone like _you_ may not understand." Claude hissed, leaning into the other's face. "Anyways, I see that you've started a family with that Phantomhive boy. That soul you so desired to devour not too long ago."

Sebastian bit his lip. "What is it that you want from me?"

Claude shrugged, the grin still plastered on his face. "Oh, nothing much… Just to see you suffer a fate worse than death. I turned down Alois Trancy's soul in an attempt to gain Ciel Phantomhive's. And yet… _You took that chance away from me." _His tone of voice morphed into a snarl. "I think that deserves a bit of payback, yes?"

"Oh? Is that a threat? I believe I'm sensing some jealousy in your voice." Sebastian sneered. "And just what are you going to do about it? My mate and daughter are both demons- there is no way in which you can even hope to do anything to them now."

"That's what you may think." Claude licked his lips, looking back into the forest. "I'd say the fire tearing down your lovely home says differently."

Sebastian's blood ran cold, all emotion leaving his face. _"What."_

"You of all people should know that a demon has only two weaknesses." Claude held up two fingers to help prove his point. "One, fire. Two, a demon's sword. Unfortunately for you, today, those two weaknesses will cost you the lives of your loving family."

And like that, Sebastian snapped.

"You bastard!" The demon screeched, running over and giving the other a swift kick to the neck. "What the fuck did you do? Stay _away_ from them!"

"Were you not listening to a word that I just said?" Claude sighed, quickly recovering from the blow. "The damage has already been done. They're already-"

But Sebastian was gone before the other demon could finish his sentence. He ran through the forest as fast as demonly possible, sweat dripping down his face as he panted heavily, the panic rising in his chest.

_Nonononononono-_

His heart nearly stopped when he finally reached his home. The entire building was almost already consumed by the fire. Ciel was nowhere to be found. Sebastian let out a cry of anguish as the next tragic scene caught his eye. Pinned to the door of his burning house by the very sword that had supposedly killed Claude was his own daughter, Layva. Blood poured out from the wound in her stomach, and a stream of the red liquid trickled down her mouth, creating a small puddle on the ground below. The child was desperately struggling to free herself from the sword's weight, but it was clear that she was growing weaker by the second.

Sebastian fell to his knees and began to sob, knowing that there was nothing he could do to help her. Tears streamed down his face as he remembered those fateful words;

_A wound caused by a demon's sword can never heal._

"Are you suffering yet?" Claude whispered, walking up behind the other demo. "Don't worry. If this hasn't affected you enough, there will surely be more to come. I can promise you that." And just like that, he vanished, never to be seen again.

Sebastian didn't even bother to turn around, let alone murder Claude for what he had done. He didn't even try to move, for he knew that he wouldn't be able to. All he could do was cry and watch as his daughter slowly withered away in front of him. So many thoughts and emotions swirled around in the demon's mind. Guilt. Hatred. Helplessness. Anguish. Suici-

"Sebastian! SEBASTIAN!" The sound of his mate's voice pierced Sebastan's heart like a thorn. The demon frantically looked around. "Ciel? Ciel? Where are you?" He immediately caught sight of the boy. Ciel was attempting to climb out the window, and serious burns were already visible on his hands, arms, and face. "What are you doing? Don't just stand there!" Ciel sobbed, motioning towards his daughter. "Save Layva! Save our baby! Can't you see she's in pain? She's struggling! Get a move on, Sebastian, HELP HER!"

Sebastian took one look at Layva and gritted his teeth, wetness filling his eyes once more. She had already stopped moving.

_There's no hope for her now. I have to abandon this and rescue Ciel… He's all I have left._

"C-Ciel.. I'm afraid I can't do that… She's already too far gone. You're my priority, and you always have been." Much to Ciel's dismay, Sebastian ran over and quickly climbed up the side of the building. It didn't take long for him to reach the window.

"What are you doing? I TOLD you to save Layva! Why won't you listen?" Ciel screamed, pounding his fists on Sebastian's back as the man tore him from the inferno. "Leave me here! I don't care if I die, just as long as she's alright! SEBASTIAN!"

Sebastian ignored him and jumped from the window an easily landed on the ground, taking off with a swift run. He turned away when he saw the mortified look on Ciel's face as they ran past their now lifeless daughter. It was all he could do to keep his own heart from bursting.

"NO! Stop, Sebastian! If you don't get her, she'll, she'll-" Ciel choked out, a river of tears splattering all over the ground.

"_LAYVA!"_

The two sat leaning up against a tree a ways away from the house, both completely numb to the core. Sebastian cradled a shaken Ciel in his arms, gently rocking him back and forth in an attempt to calm him down. No words were exchanged between the two- the magnitude of the situation was just too great to begin a conversation.

They sat in silence for what seemed like hours, until Ciel began mumbling things under his breath. "My baby.. My baby is dead.. She's dead. My baby is dead." He said almost with no emotion, hiding his face in Sebastian's chest. "I told you to save her, but you refused." His hand gripped the fabric of Sebastian's suit. "Why, Sebastian? Why didn't you help her? Did you want our baby to die? Maybe that's it…"

"Why would you ask something like that? I would never want such a terrible thing." Sebastian tightened his grip on the boy. "I don't think you understand. She was already dead by the time I arrived. There wa-"

"That's a lie." Ciel looked up; giving him the most heartless glare he could muster. "You know damn well she was still alive. We _both_ saw her struggling, and yet you did nothing to help her."

"Ciel, she was stabbed by a demon sword. A DEMON sword! Wounds caused by that blade never heal. You should know that. Even if I _had_ gotten her down, here would've been nothing we could do to help her."

"But you still could've tried. But you didn't. And now our daughter is _dead_." Ciel replied icily, shoving the older demon away.

"Ciel, you sound ridiculous.´Sebastian scoffed. "Her death was not my fault. It was the work of that despicable revenge-hungry demon, Claude. This is indeed a tragedy, yes. I don't think I've ever been so heartbroken in my entire five thousand years of life. But we're going to have to find some way to move on. Besides, we can always have more children-"

Wrong words.

The slap to the face that Ciel dealt him burned like wildfire. "We can always have more children", you say?" Ciel spat, his eyes glowing a dangerous red. "It sounds to me like Layva never meant anything to you at all, if she can be that easily replaced by another child! You're _sick_. I can't believe I ever mated with you in the first place."

Sebastian was fully frozen with shock. "Ciel.. Do you really.. Feel this way?"

"Of course I do, _idiot_." Ciel snarled and turned away. "If this is the attitude you're going to have towards such a serious incident, then get out of my sight. I never want to see your face again, you pathetic excuse of a demon."

Sebastian's entire body felt numb as he watched his former mate walk away. _I've lost everything… My house was burnt to a crisp. My daughter was murdered… And now my mate is leaving me for a misunderstanding? _

_I've been by his side for so long. And this is how…. _The man balled his hand into a fist, the familiar demonic aura surrounding his body as his rage reached its peak.

_NO. No, no, no, no, no!_

"_You fucking wretch." _Sebastian snarled, charging after Ciel and roughly grabbing him by the neck. He lifted the terrified boy into the air, receiving pleasure from the coughing sounds coming from his throat. "After all I've done for you. I formed a contract with you to help you achieve your greatest desire. I slaughtered all of your enemies and served you as a lowly butler while putting up with your constant abuse. I easily rescued you from your day-to-day scuffles. In the end, I didn't even take your soul. In fact, I grew you to love you, which I never thought was even possible for a demon. I gave you a child. On top of all of that, I just saved your life over my own flesh and blood. And THIS is how you repay me?"

Ciel could only stare, a wave of horror and guilt washing over him as he realized the magnitude of his selfishness. "Se-Sebas-"

"It no longer matters. I'm done with you." Sebastian crushed the boy's neck with a quick squeeze, feeling satisfied as he felt the body go limp in his arms. "Good. But we're not done yet." He flung Ciel over his shoulder and darted back in the direction of his burning house.

When they finally returned, the fire had somewhat gone out, and a majority of the house had been reduced to ash. Only a few of the central walls remained intact.

Tossing Ciel on the ground, Sebastian headed over to the door and tore the demon sword from his daughter's body, barely paying attention as the burnt corpse hit the ground. He walked back over to Ciel's body, and with the very sword that had killed his own daughter, he plunged it into the boy's back. A final choking noise emitted from Ciel's mouth, and that was the end of it.

Sebastian scowled, stomping on the motionless body as he turned to walk away. "Damn brat."

A final pang of sadness struck Sebastian as he strolled off into the darkness.

_In truth.. A demon's heart can only take so much._

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**((So yeah. I randomly made one of their weaknesses fire. I don't know. This was written on a whim. This is so… Depressing. Poor Sebastian.. I want to give him a hug. Honestly, I think that this is kind of bad, and I feel like a may have rushed it a bit, but I decided to post it anyway. *Sigh* Review/fave, please! I'd love to know what you think.))**


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